1. Field of the Invention
The present invention relates to a layer built cell comprising electrodes and an electrolytic solution. In particular, the present invention relates to a layer built cell with improved safety.
2. Description of the Related Art
A layer built cell comprising lithium as a negative electrode active material, manganese dioxide as a positive electrode active material and an organic solvent electrolytic solution, a typical example of which is a lithium-manganese dioxide cell, is increasingly used, since it has a high energy density, a light weight and a long life.
Recently, attentions are paid on the use of a layer built cell comprising an organic electrolytic solution as a secondary cell, and such cell is commercially sold as a lithium ion cell. The lithium ion cell uses LiCoO.sub.2 as a positive electrode and a carbon compound as a negative electrode and can generate a high voltage.
With the increase of a cell density and improvement of discharge characteristics of such cell, the cell tends to lose its safety. With the increase of the density, the electrolytic solution may not be sufficiently penetrated in the entire volume of the cell.